Panda type separated-circles-formed elliptical ring core few-mode fiber

To support large transmission and reduce inter-mode crosstalk, we designed a polarization-maintaining few-mode fiber (PM-FMF) with a separated-circles-formed elliptical ring core and two stress rods. This fiber can support ten different polarization modes with tunable chromatic dispersion. With the stress-rods-induced birefringence and the high refractive index difference of 0.03 between the core and the cladding, the fiber can separate adjacent guided modes from each other. The effective refractive index differences between these modes all remain above 1.2 × 10−4 over the entire C + L band. In addition, the special separated-circles-formed elliptical ring structure of this few-mode fiber can provide a new degree of freedom for the regulation of chromatic dispersion. The chromatic dispersion can be simply adjusted by changing the radius of the small circles.